DAC Recommendation for DIY media player with Raspberry Pi and miniDSP balanced

[PeetSahat]

Thanks! That makes sense. Although it doesn't seem logical to me to provide the prescaler also in master mode. My guess was that in master mode the prescaler reduces the internal MCLK. There are 20 different firmwares to be selected within the maintenance tool. The documentation is truly sparse to nonexistent to say the least.
It might be best to message the developer and ask for advice.

 

[TaxTime]

I don't PERSONALLY think the clock frequency, in this case, would be a problem since it's 2x the needed frequency. But I'm not a digital engineer, and I also don't play one on TV or on YouTube.

 

[mdsimon2]

I don't PERSONALLY think the clock frequency, in this case, would be a problem since it's 2x the needed frequency. But I'm not a digital engineer, and I also don't play one on TV or on YouTube.

That has not been my experience at all when dealing with I2S. Datasheets are usually very clear on the clocking requirements and miniDSP says 12.288 MHz. It is also clear that the default miniDSP firmware is for the 2x4 to act as master and special firmware needs to be loaded if using in slave mode. @PeetSahat did you use the slave firmware for the miniDSP?

I dug out my Amanero and confirmed CPLD MasterDF1706 + CPU Firmware 1.074 gives a 12.288 master clock for 48 kHz output (only confirmed on scope, did not listen to this).

I also tried the CPLD Master12288 with CPU Firmware 1.080, however when set to 48 kHz, this output 24.576 MHz master clock and BLCK and LRCLK were double the frequency they should be (6.144 MHz and 96 kHz respectively). After looking at the notes in the firmware update tool, I think this firmware is actually for use with physical 12.288 / 11.2896 MHz oscillators and NOT when you are trying to output those frequencies on the clock pin from the existing 24.576 / 22.5792 MHz oscillators. It seems possible that the Slave12288 firmware might work for your case if using the 2x4 as clock master and the Amanero as slave.

I'd probably stick with MasterDF1706 unless you need slave mode.

Michael

 

[PeetSahat]

did you use the slave firmware for the miniDSP?

Not yet. I'm still figuring out how to connect the Amanero to the minidsp physically. When the connection is confirmed I will move on to the software settings.

The minidsp must be slave as it doesn't provide a master clock output.

Thanks for your effort! That's a huge help.

 

[mdsimon2]

Your connections look correct to me. You may want to play around with ground connections, I would probably try running one ground connection for each of MCLK, BCLK, LRCLK and data. I think there are enough connections on the Amanero to do it.

Michael

 

[PeetSahat]

Will give it a shot. Thanks!

 

[PeetSahat]

did you use the slave firmware for the miniDSP?

I got it to work after contacting the developer. Very helpful guy. He provided the correct firmware and an updated configuration tool.

The correct firmware to use is

CPLD: CPLD_1080_DIV2
CPU: firmware_1096c3w2

Here's the link to the new configuration tool:

http://www.amanero.com/update118new.zip

Bypassing that on-board ADC is a huge step forward soundwise. Maybe I can establish an external power supply for the Amanero which should have a positive impact as well.

 

[mdsimon2]

Glad to hear you got it up and running! Did you need to change to the slave firmware on the 2X4 as well?

Michael

 

[PeetSahat]

Did you need to change to the slave firmware on the 2X4 as well?

Yep. The DSP has to run in slave mode as it cannot provide a master clock.
Slave mode is engaged by changing a jumper position on the board.

 

[PeetSahat]

Now that the connection is working, I need to find a way to delay the power supply to the miniDSP
as it needs a stable master clock input to boot up correctly. If switched on too early the boot process is corrupted
and the DSP has to be re-flashed.
Currently I'm using an older barebone PC running Win10. I wonder when Windows powers up all USB accessories correctly.
I waited around 10 seconds after switching it on. 10 seconds is the maximum delay of the relay module I bought.
But apparently that was too short. So I need a relay with a longer delay.
Later on this setup will be used with a RPi3B+ so the delay needed might change anyway.

 

[PeetSahat]

I'm on the verge of abandoning this project since achieving a correct boot-up with the miniDSP and I2S signal input seems nearly impossible. Despite patiently waiting for a stable master clock, the device refuses to boot consistently. Occasionally, it does work, but the success is not reproducible. I experimented with switching to an RPi, and it worked a few times. Subsequently, I attempted using an ADC with I2S output as a second source, which initially worked, but now faces the same issue. To rule out a board-specific problem, I tested another miniDSP, but encountered the identical behavior. Having to reload the configuration to the board via USB every time is highly impractical.